Carbazole containing benzopyrans

ABSTRACT

Benzopyrans of the formula ##STR1## where X is a radical ##STR2## and R 1 , R 2 , R 3 , R 4  and the ring A have the meanings stated in the description, a process for their preparation, and their use in pressure-sensitive or heat-sensitive layers.

The present invention relates to novel benzopyrans which have a side chain in ring position 2, a process for their preparation and their use in pressure-sensitive or heat-sensitive recording systems.

We have found benzopyrans of the general formula I ##STR3## where R¹ is unsubstituted or substituted C₁ -C₈ -alkyl, unsubstituted or substituted phenyl, C₁ -C₅ -alkoxy or halogen, X is a radical ##STR4## R² is hydrogen or, together with R¹, is C₂ -or C₃ -alkylene which is unsubstituted or substituted by C₁ -C₄ -alkyl, R³ is phenyl which is unsubstituted or substituted by C₁ -C₄ -alkyl (which in turn may be substituted by phenyl), cyclohexyl, halogen, C₁ -C₈ -alkoxy, C₁ -C₈ -mono- or dialkylamino (each of which in turn may be substituted by phenyl or chlorine), phenylamino (which in turn may be substituted by C₁ -C₈ -alkyl on the phenyl ring or on the nitrogen atom), pyrrolidino, piperidino or morpholino, and which furthermore may be substituted by C₁ -C₅ -alkyl, C₁ -C₅ -alkoxycarbonyl, C₁ -C₅ -dialkylaminocarbonyl, pyrrolidinocarbonyl, piperidinocarbonyl, morpholinocarbonyl, C₁ -C₈ -alkoxy or halogen; or is naphthyl which is unsubstituted or substituted by C₁ -C₄ -alkoxy; or is carbazol-3-yl or 1,2,3,4,4a,9a-hexahydrocarbazol-6yl, each of which may be substituted on the nitrogen atom by C₁ -C₅ -alkyl or benzyl, or is indol-3-yl, which may be substituted in ring position 1 and/or 2 by unsubstituted or phenyl-substituted C₁ -C₅ -alkyl; or is thiazol-5-yl which is substituted in ring position 2 by unsubstituted or phenyl-substituted C₁ -C₅ -mono- or dialkylamino, pyrrolidino, piperidino or morpholino and may be substituted in ring position 4 by C₁ -C₅ -alkyl, phenyl or chlorine, and R⁴ is hydroxyl, C₁ -C₅ -alkoxy, unsubstituted or substituted phenoxy, unsubstituted or substituted phenylsulfonyl, pyrrolidino, piperidino, morpholino or a radical of a CH-acidic compound, and the ring A may be fused to a benzo ring, may be substituted by C₁ -C₄ -alkyl, chlorine or bromine, or may be substituted in ring position 7 by C₁ -C₅ -mono- or dialkylamino (each of which in turn may be substituted by chlorine or phenyl), pyrrolidino, piperidino, morpholino, hydroxyl or C₁ -C₄ -alkoxy.

All alkyl groups occurring in the abovementioned radicals may be either straight-chain or branched.

In formula I, R¹ is, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, isoamyl, hexyl, heptyl, octyl, 2-ethylhexyl, phenyl which is unsubstituted or substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or halogen, such as 4-methylphenyl, 2-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-methoxyphenyl, 2-ethoxyphenyl, 4-chlorophenyl or 2,4-dichlorophenyl, methoxy, ethoxy, propoxy, isopropoxy, butoxy, fluorine, chlorine or bromine.

In formula I, R² is, for example, hydrogen or, together with R¹, is 1,2-ethylene, 1,2-propylene or 1,3-propylene.

In formula I, R³ is, for example, phenyl or, preferably, phenyl which is substituted in ring position 4 by methyl, ethyl, propyl, isopropyl, butyl, sec-butyl, benzyl, 2-phenylethyl, cyclohexyl, fluorine, chlorine, bromine, methoxy, ethoxy, propoxy, isopropoxy, butoxy, pentyloxy, hexyloxy, 2-ethylhexyloxy, methylamino, ethylamino, isopropylamino, butylamino, 2-ethylhexylamino, benzylamino, 2-chloroethylamino, dimethylamino, diethylamino, dibutylamino, methylethylamino, di(2-ethylhexyl)-amino, anilino, 4-methylanilino, 4-ethylanilino, N-methylanilino, N-ethylanilino, pyrrolidino, piperidino or morpholino; or is, for example, 2,4-dimethylphenyl, 2-methoxycarbonyl-4-dimethylaminophenyl, 2-ethoxycarbonyl-4-dimethylaminophenyl, 2-dimethylaminocarbonyl-4-methoxyphenyl, 2-pyrrolidinocarbonyl-4-methylphenyl, 2-piperidinocarbonyl-4-dimethylaminophenyl, 2-morpholinocarbonyl-4-methylphenyl, 2,4-dimethoxyphenyl, 3,4-dimethoxyphenyl, 2-methoxy-4-dimethylaminophenyl, 2-methoxy-4-dibenzylaminophenyl, 2,4-dichlorophenyl, naphthyl, 4-methoxynaphthyl, carbazol-3-yl, N-methylcarbazol-3-yl, N-ethylcarbazol-3-yl, N-benzylcarbazol-3-yl, 1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, N-methyl-1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, N-ethyl-1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, N-benzyl-1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, indol-3-yl, 1-methylindol-3-yl, 1-ethylindol-3-yl, 1-benzylindol-3-yl, 1=(2-phenylethyl)indol-3-yl, 2-methylindol-3-yl, 1,2-dimethylindol-3-yl, 1-benzyl-2-methylindol-3-yl, 2-methylaminothiazol-5-yl, 2-dimethylaminothiazol-5-yl, 2-diethylaminothiazol-5-yl, 2-benzylaminothiazol-5-yl, 2-pyrrolidinothiazol-5-yl, 2-morpholinothiazol-5-yl, 4-methyl-2-dimethylaminothiazol-5-yl, 4-phenyl-2-benzylaminothiazol-5-yl or 4-chloro-2-piperidinothiazol-5-yl.

In formula I, R⁴ is, for example, hydroxyl, methoxy, ethoxy, propoxy, isopropoxy, sec-butoxy or pentyloxy; phenoxy which is unsubstituted or substituted by C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or halogen, such as 2-methylphenoxy, 4-methylphenoxy, 3-methoxyphenoxy or 4-chlorophenoxy; phenylsulfonyl which is unsubstituted or substituted by C₁ -C₄ -alkyl or halogen, such as 4-methylphenylsulfonyl or 4-chlorophenylsulfonyl; pyrrolidino, piperidino or morpholino.

In formula I, R⁴ may furthermore be a radical of a CH-acidic compound, for example 2-(pyrrolidino, piperidino or morpholino)-cyclopent-1-en-1-yl or -cyclohex-1-en-1-yl; cyclohexane-1,3-dion-2-yl which is unsubstituted or monosubstituted or disubstituted in ring position 5 by C₁ -C₄ -alkyl, such as cyclohexane-1,3-dion-2-yl, 5-methylcyclohexane-1,3-dion-2-yl, 5-ethylcyclohexane-;b 1,3-dion-2-yl or 5,5-dimethylcyclohexane-1,3-dion-2-yl; benzoylmethyl; cyano; nitromethyl; 2,4,6-trihydroxypyrimid-5-yl; 1-phenyl-3-methylpyrazol-5-on-4-yl; 5-hydroxy-3,4-dichlorfuran-2-yloxy; or a radical ##STR5## where Y and Z are identical or different and independently of one another are each acetyl, benzoyl, C₁ -C₅ -alkoxycarbonyl or cyano, and, where Y is cyano, Z may furthermore be methyl, eg. bis-(acetyl-methyl, bis-(benzoyl)-methyl, bis-(methoxycarbonyl)-methyl, bis-(ethoxycarbonyl)-methyl, bis-(cyano)-methyl, acetyl-benzoyl-methyl, acetyl-methoxycarbonyl-methyl, benzoyl-ethoxycarbonyl-methyl, cyano-methoxycarbonyl-methyl or 1-cyanoeth-1-yl.

In formula I, the ring A may be substituted, for example, in ring position 6 or 8 by chlorine or bromine or in ring position 6 and 8 by chlorine. It may furthermore be substituted in ring position 7 by, for example, methyl, ethyl, propyl, isopropyl, butyl, hydroxyl, methoxy, ethoxy, isopropoxy, methylamino, ethylamino, propylamino, isopropylamino, butylamino, benzylamino, 2-chloroethylamino, dimethylamino, diethylamino, dibutylamino, dibenzylamino, methylethylamino, pyrrolidino, piperidino or morpholino. It may also be benzofused, for example as follows: ##STR6##

Preferred benzopyrans of the formula I are those in which R¹ is C₁ -C₅ -alkyl, R² is hydrogen, R³ is carbazol-3-yl or unsubstituted or substituted phenyl and R⁴ is a radical ##STR7##

The novel benzopyrans are advantageously obtained if a benzopyrylium compound of the formula II ##STR8## where R¹ and the ring A have the above meanings and Y.sup.⊖ is an anion, is reacted with an aldehyde of the formula III

    R.sup.3 --CHO                                              (III)

where R³ has the above meanings, in a molar ratio of from 1:0.8 to 1:1.2, in the presence of an inert solvent at from 20° to 120° C., preferably from 40° to 80° C., and, in a subsequent stage, the resulting dye salt of the formula IV ##STR9## where R¹, R³, Y.sup.⊖ and the ring A have the above meanings, is reacted with a compound of the formula V

    R.sup.4 --H                                                (V)

where R⁴ has the above meanings, in a molar ratio of from 1:1.1 to 1:2, in the presence of an inert solvent and of a base at from 20° to 120° C., preferably from 40° to 80° C.

Examples of suitable anions Y.sup.⊖ are trichlorozincate, tetrachloroferrate(III), bisulfate, nitrate or halide, such as chloride or bromide. Trichlorozincate and tetrachloroferrate (III) are particularly preferred.

Examples of advantageously inert solvents are methanol, ethanol, propanol, isopropanol, butanol and isobutanol. Mixtures of these alcohols with aromatic hydrocarbons, such as toluene or xylene, may also be used as the reaction medium.

Examples of suitable bases for the reaction of the dye salt IV with the compound V are alkali metal and alkaline earth metal carbonates, such as sodium carbonate, potassium carbonate, magnesium carbonate or calcium carbonate, alkaline earth metal oxides, such as magnesium oxide or calcium oxide, and alkali metal alkanolates, such as sodium or potassium methylate, ethylate or butylate. In general, from 1 to 3 moles of base are added per mole of dye salt.

The benzopyrylium salts II, aldehydes III and compounds IV which are required for the novel process are known.

The benzopyrans according to the invention are pale or colorless compounds whose solutions in inert organic solvents, in contact with electron acceptors, give dyeings in yellow, orange, red or blue hues, depending on the substitution of the benzopyran. Examples of electron acceptors are carboxylic acids, mineral acids, kaolin, bentonite, activated clay, aluminum silicate, attapulgite or any clay, acidic polymeric materials, such as condensates based on phenol (and/or phenolsulfonic acids) and formaldehyde, as well as metal oxides or salts, such as zinc oxide, alumina, zinc chloride, iron stearate and cobalt naphthenate.

Because of these propertiesm, the novel compounds of the formula I are useful as dye precursors in pressure-sensitive and heat-sensitive recording materials.

For use in pressure-sensitive systems the novel benzopyrans are advantageously enclosed in microcapsules, in the form of solutions in organic solvents, eg. chloroparaffins, partially hydrogenated di- or terphenyl, alkylbenzenes, alkylnaphthalenes, alkylated dibenzylbenzenes, liquid paraffin, mineral oil or conventional lower-boiling solvents, such as xylene or toluene, and the carrier, eg. paper, is coated with these microcapsules. When the microcapsules are subjected to pressure and are in contact with electron acceptors, dye formation then takes place at the pressure point.

Suitable processes for the preparation of microcapsules are disclosed in, for example, U.S.-A-2 800, 457, U.S.-A-2 800,458, DE-A-2 119 933 and EP-A-26 914. It is also possible for the novel compounds to be finely dispersed in wax or oil/wax mixtures by the method described in U.S.-A-3 103,404, and carriers, such as films or paper, to be coated with these mixtures. The resulting pressure-sensitive materials are suitable for copying onto papers coated with electron acceptors, and can be removed after use, like carbon paper.

The novel benzopyrans can also be used as dye precursors in heat-sensitive recording materials which contain a binder, a dye precursor and an electron acceptor on a carrier. The structure of such heat-sensitive recording materials and the composition of the layers which produce the color under the effective heat are known (for example, DE-A-2 228 581 and DE-A-2 110 854), as are the processes and apparatuses which are used to produce the dye.

The examples which follow illustrate the invention.

EXAMPLE 1 (a) Synthesis of the Dye Salt

331 g (1 mole) of 2,3-dimethylbenzopyrylium trichlorozincate and 149 g (1 mole) of 4-dimethylaminobenzaldehyde in 1,500 ml of methanol were refluxed for 4.5 hours. After the mixture had cooled, the precipitated dye was filtered off under suction and washed with methanol.

Yield: 400 g (86.6% of theory). mp.: 242°-244° C.

The dye salt of the formula ##STR10## is obtained.

(b) Synthesis of the Dye Precursor

46 g (0.1 mole) of the dye salt prepared under (a) and 20 g of benzoylacetone (0.13 mole) in 500 ml of methanol were stirred in the presence of 22 g (0.2 mole) of sodium carbonate at 45° C. The reaction mixture was then added to a mixture of 1,600 ml of toluene and 1,600 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. 500 ml of methanol were added, and the precipitate which formed was then filtered off under suction, washed with 200 ml of methanol and dried at 60° C. under reduced pressure.

Yield: 34 g (76%). mp.: 165°-167° C.

A dye precursor of the formula ##STR11## was obtained.

The components of the formula ##STR12## which are listed in Table 1 can be obtained in a similar manner.

                  TABLE 1                                                          ______________________________________                                                                          Color                                         Example                                                                               R.sup.4          Mp. [°C.]                                                                        or λ.sub.max [nm]                      ______________________________________                                                 ##STR13##       270-272  blue                                          3      CH(COC.sub.6 H.sub.5).sub.2                                                                     193-195  628.9                                         4      CH(CN).sub.2     194-196  628.9                                         5      CH.sub.2NO.sub.2 156-158  blue                                          ______________________________________                                    

EXAMPLE 6 (a) Synthesis of the Dye Salt

331 g (1 mole) of 2,3-dimethylbenzopyrylium trichlorozincate and 223 g (1 mole) of N-ethylcarbazole-3-aldehyde in 2,600 ml of methanol saturated with HCl are refluxed for 3 hours. After the mixture had cooled, the precipitated dye was filtered off under suction and washed with methanol.

Yield: 453 g (84.6% of theory). mp.: 240°-242° C.

A dye salt of the formula ##STR14## was obtained.

(b) Synthesis of the Dye Precursor

16 g (0.03 mole) of the dye salt prepared under (a) and 5 g (0.038 mole) of ethyl acetoacetate in 250 ml of methanol were stirred in the presence of 7 g (0.066 mole) of sodium carbonate at 45° C. The reaction mixture was then added to a mixture of 500 ml of toluene and 500 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. After the addition of 250 ml of methanol, the precipitate formed was filtered off under suction, washed with 70 ml of methanol and dried at 60° C. under reduced pressure.

Yield: 10 g (67.6% of theory. mp.: 132°-134° C.

A dye precursor of the formula ##STR15## was obtained.

The components of the formula ##STR16## which are listed in Table 2 can be obtained in a similar manner.

                  TABLE 2                                                          ______________________________________                                                                          Color                                         Example                                                                               R.sup.4          Mp. [°C.]                                                                        or .sub.max [nm]                              ______________________________________                                                 ##STR17##       156-158  blue                                          8      CH(COCH.sub.3).sub.2                                                                            147-149  607.4                                         9                                                                                      ##STR18##       126-128  606.9                                         10     OH               154-157  606.4                                         11     CH(COOC.sub.2 H.sub.5).sub.2                                                                    182-184  pale blue                                     12     CH(COC.sub.6 H.sub.5).sub.2                                                                     142-144  606.9                                         13     CH(CN).sub.2     241-243  607.4                                         14                                                                                     ##STR19##       193-195  607.9                                         15                                                                                     ##STR20##       187-189  607.9                                         16     CH.sub.2NO.sub.2 154-156  605.4                                         17     CH(COOCH.sub.3).sub.2                                                   ______________________________________                                    

The dye precursors of the formula ##STR21## which are listed in Table 3 can be obtained similarly to Examples 1 to 6.

                                      TABLE 3                                      __________________________________________________________________________     Example                                                                              R.sup.1   R.sup.3          R.sup.4       Mp. [°C.]                                                                     Color or                                                                       λ.sub.max          __________________________________________________________________________                                                          [nm]                      18    CH.sub.3                                                                                  ##STR22##                                                                                       ##STR23##    146-148                                                                              blue                      19    CH.sub.3                                                                                  ##STR24##       CH(COCH.sub.3).sub.2                                                                         142-144                                                                              pale lime green           20    CH.sub.3                                                                                  ##STR25##       CH(COC.sub.6 H.sub.5).sub.2                                                                  144-146                                                                              642.4                     21    CH.sub.3                                                                                  ##STR26##                                                                                       ##STR27##    203-205                                                                              blue                      21    CH.sub.3                                                                                  ##STR28##                                                                                       ##STR29##    203-205                                                                              blue                      22    CH.sub.3                                                                                  ##STR30##       CH(COCH.sub.3).sub.2                                                                         170-172                                                                              blue                      23    CH.sub.3                                                                                  ##STR31##                                                                                       ##STR32##    144-148                                                                              green                     24    CH.sub.3                                                                                  ##STR33##       CH(COC.sub.6 H.sub.5).sub.2                                                                  189   632.4                     25    CH.sub.3                                                                                  ##STR34##                                                                                       ##STR35##    184-186                                                                              blue                      26    CH.sub.3                                                                                  ##STR36##                                                                                       ##STR37##    oil   672.9/631.4               27    CH.sub.3                                                                                  ##STR38##                                                                                       ##STR39##    128-130                                                                              671.9/630.9               28    CH.sub.3                                                                                  ##STR40##       CH(COC.sub.6 H.sub.5).sub.2                                                                  132-134                                                                              672.9/630.4               29    CH.sub.3                                                                                  ##STR41##       CH(CN).sub.2  203-205                                                                              blue                      30    CH.sub.3                                                                                  ##STR42##                                                                                       ##STR43##    oil   blue                      31    CH.sub.3                                                                                  ##STR44##                                                                                       ##STR45##    oil   blue                      32    CH.sub.3                                                                                  ##STR46##                                                                                       ##STR47##    154-156                                                                              blue                      33    CH.sub.3                                                                                  ##STR48##       OH            195   blue                      34    CH.sub.3                                                                                  ##STR49##       CH(COC.sub.6 H.sub.5).sub.2                                                                  178-180                                                                              519.3                     35    CH.sub.3                                                                                  ##STR50##       CH(COCH.sub.3).sub.2                          36    CH.sub.3                                                                                  ##STR51##                                                                                       ##STR52##                                    37    CH.sub.3                                                                                  ##STR53##       CH(COCH.sub.3).sub.2                                                                         165   reddish violet            38    CH.sub.3                                                                                  ##STR54##                                                                                       ##STR55##          reddish violet            39     CH.sub.3                                                                                 ##STR56##       CH(COCH.sub.3).sub.2                                                                          98-102                                                                              523.8                     40    CH.sub.3                                                                                  ##STR57##                                                                                       ##STR58##    159-160                                                                              reddish violet            41    CH.sub.3                                                                                  ##STR59##       OH            136-140                                                                              pale red                  42    CH.sub.3                                                                                  ##STR60##                                                                                       ##STR61##    oil   542.8                     43    CH.sub.3                                                                                  ##STR62##       OH            120-124                                                                              reddish violet            44    CH.sub.3                                                                                  ##STR63##       CH(COCH.sub.3).sub.2                                                                               violet                    45    CH.sub.3                                                                                  ##STR64##       OH            210-216                                                                              violet                    46    CH.sub.3                                                                                  ##STR65##       CH(COCH.sub.3).sub.2                                                                         141-145                                                                              pink                      47    CH.sub.3                                                                                  ##STR66##       CH(COCH.sub.3).sub.2                                                                         oil   orange                    48    CH.sub.3                                                                                  ##STR67##       OH            oil   orange                    49    CH.sub.3                                                                                  ##STR68##       CH(COCH.sub.3).sub.2                                                                         118   yellow                    50    CH.sub.3                                                                                  ##STR69##                                                                                       ##STR70##    155   yellow                    51    CH.sub.3                                                                                  ##STR71##                                                                                       ##STR72##    163-168                                                                              647.9                     52    CH.sub.3                                                                                  ##STR73##       CH(COCH.sub.3).sub.2                                                                         oil   blue                      53    CH.sub.3                                                                                  ##STR74##                                                                                       ##STR75##    oil   blue                      54    CH.sub.3                                                                                  ##STR76##                                                                                       ##STR77##    181-183                                                                              blue                      55    CH.sub.3                                                                                  ##STR78##       CH(COCH.sub.3).sub.2                                                                         130-132                                                                              blue                      56    CH.sub.3                                                                                  ##STR79##       CH(COC.sub.2 H.sub.5).sub.2                                                                  166-168                                                                              644.9                     57    CH.sub.3                                                                                  ##STR80##       CH(CN).sub.2  221-223                                                                              643.9                     58    CH.sub.3                                                                                  ##STR81##       CH(COCH.sub.3).sub.2                                                                         198-200                                                                              573.3                     59    CH.sub.3                                                                                  ##STR82##                                                                                       ##STR83##    134-137                                                                              violet                    60    CH.sub.3                                                                                  ##STR84##                                                                                       ##STR85##          blue                      61    CH.sub.3                                                                                  ##STR86##                                                                                       ##STR87##    204-207                                                                              violet 549.3/583.8        62    CH.sub.3                                                                                  ##STR88##                                                                                       ##STR89##    oil   blue                      63    CH.sub.3                                                                                  ##STR90##                                                                                       ##STR91##    oil   blue                      64    CH.sub.3                                                                                  ##STR92##                                                                                       ##STR93##    oil   blue                      65    CH.sub.3                                                                                  ##STR94##       OH            215   violet                    66    C.sub.2 H.sub.5                                                                           ##STR95##                                                                                       ##STR96##    148-150                                                                              blue                      67    C.sub.2 H.sub.5                                                                           ##STR97##       CH(COCH.sub.3).sub.2                                                                         128-130                                                                              blue                      68    C.sub.2 H.sub.5                                                                           ##STR98##                                                                                       ##STR99##    166-168                                                                              blue                      69    C.sub.2 H.sub.5                                                                           ##STR100##      CH(COCH.sub.3).sub.2                                                                         131-135                                                                              blue                      70    CH(CH.sub.3).sub.2                                                                        ##STR101##                                                                                      ##STR102##   157-159                                                                              blue                      71    CH(CH.sub.3).sub.2                                                                        ##STR103##      CH(COCH.sub.3).sub.2                                                                         133-135                                                                              blue                      72    CH(CH.sub.3).sub.2                                                                        ##STR104##                                                                                      ##STR105##   153-155                                                                              633.4                     73    CH(CH.sub.3).sub.2                                                                        ##STR106##      CH(CN).sub.2  195-197                                                                              633.4                     74    CH(CH.sub.3).sub.2                                                                        ##STR107##                                                                                      ##STR108##   129-131                                                                              sky blue                  75    CH(CH.sub.3).sub.2                                                                        ##STR109##      CH(COCH.sub. 3).sub.2                                                                        148-150                                                                              sky blue                  76    CH(CH.sub.3).sub.2                                                                        ##STR110##      CH(COCH.sub.3).sub.2                                                                         164-168                                                                              blue                      77    CH(CH.sub.3).sub.2                                                                        ##STR111##                                                                                      ##STR112##   118-120                                                                              605.4                     78    CH(CH.sub.3).sub.2                                                                        ##STR113##      CH(COC.sub.6 H.sub.5).sub.2                                                                  143-145                                                                              606.4                     79    CH(CH.sub.3).sub.2                                                                        ##STR114##                                                                                      ##STR115##   141-143                                                                              pale blue                 80    CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR116##                                                                                      ##STR117##   140-142                                                                              blue                      81    CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR118##      CH(COCH.sub.3).sub.2                                                                         oil   blue                      82    CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR119##                                                                                      ##STR120##   163-165                                                                              pale blue                 83    CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR121##      CH(COCH.sub.3).sub.2                                                                         oil   greenish blue             84    CH.sub.2CH(CH.sub.3).sub.2                                                                ##STR122##      CH(COCH.sub.3).sub.2                                                                         oil   blue to bluish                                                                 green                     85                                                                                    ##STR123##                                                                               ##STR124##      CH(COCH.sub.3).sub.2                                                                         oil   blue                      86                                                                                    ##STR125##                                                                               ##STR126##                                                                                      ##STR127##   oil   blue                      87                                                                                    ##STR128##                                                                               ##STR129##      CH(COCH.sub.3).sub.2                                                                         oil   blue                      88                                                                                    ##STR130##                                                                               ##STR131##                                                                                      ##STR132##   oil   blue                      89                                                                                    ##STR133##                                                                               ##STR134##                                                                                      ##STR135##   179-181                                                                              greenish blue             90                                                                                    ##STR136##                                                                               ##STR137##      CH(COCH.sub.3).sub.2                                                                         oil   greenish blue             91                                                                                    ##STR138##                                                                               ##STR139##      OCH.sub.3           greenish blue             92                                                                                    ##STR140##                                                                               ##STR141##                                                                                      ##STR142##   oil   greenish blue             93                                                                                    ##STR143##                                                                               ##STR144##                                                                                      ##STR145##   180-182                                                                              blue                      94                                                                                    ##STR146##                                                                               ##STR147##                                                                                      ##STR148##   198-200                                                                              blue                      95                                                                                    ##STR149##                                                                               ##STR150##      CH(COCH.sub.3).sub.2                                                                         162-164                                                                              blue                      96    OCH.sub.3                                                                                 ##STR151##                                                                                      ##STR152##   182   blue                      97    OCH.sub.3                                                                                 ##STR153##      CH(COCH.sub.3).sub.2                                                                         168-170                                                                              blue                      98    OCH.sub.3                                                                                 ##STR154##                                                                                      ##STR155##   100-112                                                                              blue                      99    OCH.sub.3                                                                                 ##STR156##      CH(COCH.sub.3).sub.2                                                                         oil   blue                      100   OCH.sub.3                                                                                 ##STR157##      CH(COCH.sub.3).sub.2                                                                         183-185                                                                              blue                      __________________________________________________________________________

EXAMPLE 101

The following dye precursor was obtained similarly to Example 1: ##STR158##

EXAMPLE 102 (a) Synthesis of the Dye Salt

24 g (0.1 mole) of bis-(4-formylphenyl)-methylamine and 66 g (0.2 mole) of 2,3-dimethylbenzopyrylium trichlorozincate in 200 ml of methanol were refluxed for 3 hours, 200 ml of methylglycol were added and refluxing was then continued for a further 1/2 hour. The mixture was cooled, and the solvent was then separated off from the precipitated dye.

Yield: 66 g. mp.: 110° C.

(b) Synthesis of the Dye Precursor

26 g (0.03 mole) of the dye salt prepared under (a) and 8 g (0.08 mole) of acetylacetone were heated at 50° C. for 3 hours in the presence of 14 g (0.13 mole) of sodium carbonate in a mixture of 200 ml of methanol and 100 ml of toluene. The reaction mixture was then added to a mixture of 500 ml of toluene and 500 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. The residue was added dropwise to ice-cooled methanol, and the precipitate formed was filtered off under suction at 0° C.

Yield: 7 g. mp.: 166°-168° C.

A dye precursor of the formula ##STR159## was obtained.

EXAMPLE 103

The dye salt prepared in Example 102a was used and the following dye precursor was obtained by a method similar to that described in Example 102b: ##STR160##

EXAMPLE 104 (a) Synthesis of the Dye Salt

66 g (0.2 mole) of 2,3-dimethylbenzopyrylium trichlorozincate and 33 g (0.1 mole) of ethylenebis-[N-ethyl-N-(4-formylphenyl)]-amine in 400 ml of methanol were refluxed for 4 hours. After the mixture had cooled, the precipitated dye was filtered off under suction and washed with methanol.

Yield: 82 g. mp.: 255°-260° C.

(b) Synthesis of the Dye Precursor

28.5 g (0.03 mole) of the dye salt prepared under (a) and 13 g (0.08 mole) of benzoylacetone were stirred under reflux for 7 hours in the presence of 15 g (0.14 mole) of sodium carbonate in a mixture of 350 ml of methanol and 100 ml of toluene. The reaction mixture was then added to a mixture of 500 ml of toluene and 500 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. The residue was diluted with methylglycol, and methanol was added. The precipitate formed was filtered off under suction, washed with methanol and dried at 60° C. under reduced pressure.

Yield: 7 g. mp.: 132°-140° C.

A dye precursor of the formula ##STR161## was obtained.

EXAMPLE 105 (a) Synthesis of the Dye Salt

21.9 g (0.05 mole) of 2-cyclohexylidene-2,3,4,5-tetrahydroxanthylium trichlorozincate and 7.2 g (0.05 mole) of indoline-3-carbaldehyde in 320 ml of n-butanol were refluxed for one hour. The dye precipitated after the mixture had been cooled was filtered off under suction.

Yield: 21 g. mp.: 243°-245° C.

A dye salt of the formula ##STR162## was obtained.

(b) Synthesis of the Dye Precursor

9.7 g (0.02 mole) of the dye salt prepared under (a) and 2.7 g (0.027 mole) of acetylacetone in 100 ml of methanol were stirred in the presence of 4.7 g (0.044 mole) of sodium carbonate for 4 hours at 45° C. The reaction mixture was then added to a mixture of 300 ml of toluene and 300 ml of water. The organic phase was separated off, treated with active carbon and filtered, and the filtrate was evaporated down. After the addition of 100 ml of methanol, the precipitate formed was filtered off under suction, washed with 40 ml of methanol and dried at 60° C. under reduced pressure.

Yield: 5 g. mp.: 162°-170° C.

A dye precursor of the formula ##STR163## was obtained. 

We claim:
 1. A benzopyran of the formula I ##STR164## where R¹ is unsubstituted C₁ -C₈ -alkyl, unsubstituted or substituted phenyl, C₁ -C₅ -alkoxy or halogen, X is a radical ##STR165## R² is hydrogen or, together with R¹, is C₂ --R³ is carbazol-3-yl or 1,2,3,4,4a,9a-hexahydrocarbazol-6-yl, each of which may be substituted on the nitrogen atom by C₁ -C₅ -alkyl or benzyl, and the ring A may be fused to a benzo ring, may be substituted by C₁ -C₄ -alkyl, chlorine or bromine, or may be substituted in ring position 7 by C₁ -C₅ -mono- or dialkylamino (each of which in turn may be substituted by chlorine or phenyl), pyrrolidino, piperidino, morpholino, hydroxyl or C₁ -C₄ -alkoxy. 